1. Field of the Invention
This application relates to an adjustment device for adjusting the rotational position of a seat and more particularly to a novel and simple rotational adjustment device for adjusting the position of a seat relative to a pedestal.
2. Prior Art Statement
Persons with partial and total walking disabilities have traditionally relied upon wheelchairs for locomotion. Wheelchairs generally have relatively widely spaced wheels for lateral stability and to comfortably accommodate the occupant. Persons in wheelchairs can move with relative ease in places such as hospitals which are usually provided with extra wide doors and halls and inclined ramps between vertically displaced levels. However, private homes and work places are generally not planned specifically to accommodate wheelchairs. While wheelchairs are generally resistant to lateral tipping, wheelchairs are often designed for tipping backwards so that an attendant pushing a patient in a wheelchair can tip the front wheels up to negotiate such obstacles as steps, thresholds, and the like. While such a configuration is useful when the wheelchair is pushed by an attendant, the design presents some hazards when the wheelchair occupant attempts to wheel himself up a ramp.
In order to overcome some of the problems associated with wheelchairs, the medical equipment industry has developed small personal mobility vehicles as an alternative. Such vehicles generally have a pair of powered rear wheels and a steerable front wheel and in general have the appearance of a downsized golf cart. The track of the rear wheels is generally narrower than a wheelchair, the wheel base is generally longer than a wheelchair, and the vehicles are usually designed for tight turning radii such that the vehicles are more maneuverable than a wheelchair and, therefore, more useful in places which are not specifically designed for wheelchair use.
Many personal mobility vehicles have a conventional seat mounted upon a pedestal extending from a frame of the personal mobility vehicles. The conventional seat is similar to a conventional chair having a back portion and a seat portion. Typically, the seat is rotational relative to the frame.
Various types of devices have been provided by the prior art for adjusting the rotational position of the seat relative to the frame. Many of these devices incorporated complex lever assembly for adjusting the rotational position of the seat relative to the frame. Others in the prior art have attempted to use other devices to adjust the rotational position of the seat relative to the frame.
U.S. Pat. No. 809,444 to Hanger discloses a chair, the combination of a base, a support revolvable mounted on the base, a back hinged to the support, the support extending underneath the seat and being hinged to the back at or near a line passing through the vertical center thereof, means for adjusting the seat and back relatively to each other, and means for securing the back and seat against movement after the desired adjustment has been made, substantially as described.
U.S. Pat. No. 1,674,686 to Masury discloses a combination with the back and arm frames of a hammock, of a member secured to the back and having a cam face extending toward the forward side of the back and a stud, the cam face being eccentric with relation to the stud, a co-acting socket member secured to the arm frame and having an opening to receive the stud, the cam face being arranged to engage with a part carried by the arm frame.
U.S. Pat. No. 2,845,990 to Hubert discloses a vehicle seat construction comprising: a longitudinally extending platform member adapted for affixment to a vehicle; a base-plate member positioned over the platform member, means adjustably attaching the base-plate to the platform and operative to permit relative fore-and-aft movement between the base-plate and the platform; releasable pin means interlocking the base-plate to the platform in any one of a plurality of fore-and-aft displaced positions of the base-plate relative to the platform; a seat; mounting means pivotally mounting the seat above the base-plate to permit rotation of the seat about a vertical axis; the pivotal mounting means being disposed so that the vertical axis about with the seat rotates falls within the perimeter of the seat and additionally is transversely displaced a substantial distance from a vertically and longitudinally extending plane that passes through the fore-and-aft axis of symmetry of the seat; and releasable means operative to interlock the seat with the mounting means in any one of a plurality of relative rotated positions therebetween.
U.S. Pat. No. 3,975,050 to McKee discloses a unit of hardware for reclinably adjustable seating of vehicle driver and/or passenger and adapted to be swiveled into selected position, and comprising a pedestal rotatably receiving a socket positionably locked thereto, and a stop plate positionably locked in reclined positions by a toggle pin carried into tight engagement therewith by a manually releasable lever operated shackle, the tilt being positively restricted.
U.S. Pat. No. 4,231,539 to Sandham discloses an improved seat base for a swivel type seat in which the base""s seat support and pedestal are connected together in swivel relation by a thrust bearing of inverted conical configuration. In preferred form, a latch dog is movable between a latch position defined by a latch seat in the outer bearing collar for preventing swivel type rotation of the seat, and a release position where the latch dog is withdrawn from the latch seat into the interior of the thrust bearing for allowing swivel type rotation of the seal. The latch dog is pivotable on a horizontal axis oriented above the thrust bearing between those two positions through a latch post in the inner bearing collar by use of a lift arm connected thereto, the lift arm having a handle located adjacent to the seat""s front edge.
U.S. Pat. No. 4,518,139 to Barfell discloses an improved pedestal for a rotatable seat which includes a shiftable pivot arm and associated latch part. The arm and latch cooperate with a flange of the pedestal support member to secure the plate against detachable lifting during normal seat rotation.
U.S. Pat. No. 5,733,006 to Woods discloses a seat swivel assembly which allows a seat to swivel between stationary positions or to freely swivel about an axis, having an upper swivel plate and a lower swivel plate, a swivel member rotatably mounted to one of the plates, a swivel actuator lever in communication with the swivel member, a free-swivel latch facilitating unencumbered free swivel of the swivel plate, and a release lever in communication with the free swivel latch to release the swivel member to prevent free swivel.
Unfortunately, many of these devices have the distinct disadvantage of being overly complex, heavy and expensive. In addition, these devices did not have the ability for accommodating for a right-handed or a left-handed operator sitting in the chair.
One important application for an adjustment device for adjusting the rotational position of a seat relative to a frame is in the application of personal mobility vehicles. A personal mobility vehicle presents special concerns in the design of an adjustment device for adjusting the rotational position of a seat relative to a frame. Firstly, a personal mobility vehicle must be light weight to provide utmost convenience for the user. Secondly, the operation of the adjustment device must be simple to allow adjustment with the minimum number of tools. Thirdly, the adjustment device must provide a positive support in the remote event of any slippage of the adjustment device. Fourthly, the adjustment device must have the ability for accommodating for a right-handed or a left-handed operator sitting in the seat
Therefore it is an object of the present invention to provide an adjustment device for adjusting the rotational position of a seat wherein the adjustment device comprises a flange having a plurality of notches cooperating with a lever having a notch pin for engaging with one of the plurality of notches for locking the rotational position of the seat.
Another object of this invention is to provide an adjustment device for adjusting the rotational position of a seat wherein the seat may be secured in a number of rotational positions.
Another object of this invention is to provide an adjustment device for adjusting the rotational position of a seat wherein the adjustment device must have the ability for accommodating for a right-handed or a left-handed operator sitting in the seat.
Another object of this invention is to provide an adjustment device for adjusting the rotational position of a seat wherein the adjustment device is fail safe to limit the rotational movement of the seat.
Another object of this invention is to provide an adjustment device for adjusting the rotational position of a seat wherein the rotational position of the seat is automatically secured in the next rotational position.
Another object of this invention is to provide an adjustment device for adjusting the rotational position of a seat wherein the adjustment device has the ability for accommodating for a right-handed or a left-handed operator sitting in the seat.
Another object of this invention is to provide an adjustment device for adjusting the rotational position of a seat which is economical and easy to manufacture.
Another object of this invention is to provide an adjustment device for adjusting the rotational position of a seat which is light weight for use on personal mobility vehicles.
The foregoing has outlined some of the more pertinent objects of the present invention. These objects should be construed as being merely illustrative of some of the more prominent features and applications of the invention. Many other beneficial results can be obtained by applying the disclosed invention in a different manner or modifying the invention with in the scope of the invention. Accordingly other objects in a full understanding of the invention may be had by referring to the summary of the invention and the detailed description describing the preferred embodiment of the invention.
A specific embodiment of the present invention is shown in the attached drawings. For the purpose of summarizing the invention, the invention relates to an apparatus for adjusting the rotational position of a chair comprising a pedestal defining a pedestal axis extending through the pedestal. A flange is supported by the pedestal with the flange extending radially outwardly relative to the pedestal axis. A seat base is adapted to be secured to the seat with a shaft extending from the seat base and adapted for rotational connection with the pedestal for enabling the seat to rotate relative to the pedestal. A plurality of notches are defined in a spaced apart relationship about the flange. A lever has a handle portion located at a first end of the lever and a notch pin located at a second end of the lever with a lever pivot defined therebetween. A right and a left pivot mounting are defined in the seat base. The lever pivot is secured to one of the right and left pivot mountings for mounting the lever pivot in one of a right position and a left position on the seat base for accommodating for a right-handed operator or a left-handed operator seated in the chair. The notch pin engages with one of the plurality of notches for locking the rotational position of the seat base relative to the pedestal.
In a more specific example of the invention, the pedestal is a hollow tube being in a substantially vertical orientation. The shaft extends from the seat base for insertion into the pedestal for rotationally mounting the seat base relative to the pedestal. The shaft is removable from the pedestal for removing the seat from the pedestal. The flange is formed of a metallic material and the seat base has a portion formed from a polymeric material for providing a rotational bearing surface with the flange. The notch pin includes an enlarged end having a greater dimension than the notch for inhibiting removal of the seat base from the pedestal when the notch pin is engaged with the notch.
The flange is a substantially circular flange having an outer circumference with the plurality of notches extending radially inwardly from the outer circumference of the substantially circular flange. Preferably, each of the notches is tapered for facilitating insertion of the notch pin within the notch and for positively locking the notch pin within the notch.
In one example of the invention, the lever is a generally linear flat linear member being symmetric for accommodating for a right-handed operator or a left-handed operator seated in the chair when the lever is secured to one of the right and left positions on the seat base. The right and left pivot mounting includes a right and a left aperture. A shoulder bolt affixes the lever pivot to one of the right and left apertures for pivoting the lever in one of a right position and a left position on the seat base.
A spring coacts between the seat base and the lever for urging the notch pin into engagement with the notch. The lever includes a first and a second lever respite for receiving one end of a spring. A right and a left seat base respite are defined in the seat base for receiving another end of the spring. The spring is contained between the one of the lever respites and one of the seat base respites for urging the notch pin into engagement with the notch.
The foregoing has outlined rather broadly the more pertinent and important features of the present invention in order that the detailed description that follows may be better understood so that the present contribution to the art can be more fully appreciated. Additional features of the invention will be described hereinafter which form the subject matter of the invention. It should be appreciated by those skilled in the art that the conception and the specific embodiments disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention.